Computer users desire the ability to permit multiple users to review and edit documents at the same time. However, in order to avoid the situation in which two users make conflicting changes to the same document, safeguards have been implemented to prohibit a second user from accessing a document that is currently opened by another user. This has been accomplished in the past by locking the document when it is being edited by any user and prohibiting subsequent attempts to open the document. Unfortunately, this solution does not provide for simultaneous multi-user review and edit of a particular document. Because only one user can open and edit the document at any given time, this approach only provides for sequential multi-user editing. Simultaneous multi-user editing has been enabled through at least two other approaches.
One approach utilizes a central server process that permits users to merge local changes back into a shared copy of the document (the original document). Under this approach, when one user attempts to save changes to the document, the central server process attempts to store the user's changes to the original document. If the original document has been edited since the user opened its local copy, the user is notified of a potential conflict. Upon notification, the user can choose which version to store as the original document. Alternatively, the central server process can attempt to merge the changes in the user's local copy with the changes made in the modified original documents. Unfortunately, this approach is unacceptable to many users, because it requires the user to implement a central document repository for managing the document library. The repository may require a separate central server (or access monitor) to handle the requests for checking documents in and out of the repository. This process is consumptive of system resources and can slow user access to documents.
A second approach involves the use of a specialized file format that supports multi-user editing. For example, MICROSOFT EXCEL utilizes a special format referred to as a “shared workbook” that supports multi-user editing. Unfortunately, this approach is often unacceptable to users because a new file format may not be compatible with the user's earlier, non-multi-user file formats. Users are typically unwilling to utilize file formats that are not compatible with previously used file format. In addition, often the multiple user file format will have limited functionality as compared with non-multi-user file formats. That is, many of the special features of non-multi-user file formats will be disabled, because they tend to create more conflicts when changes are merged.
Therefore, there is a need for a means for enabling simultaneous multi-user editing that does not require a new file format and does not require a central server process.